Electric razor

ABSTRACT

An electric razor having a cutter foil and a cutter head, which interacts with the cutter foil and is driven by a motor which is electronically pulsed. An indicating device is provided which is connected to an operating time counter and/or to a device for detecting the load on the cutter foil and to an evaluation circuit, as a result of which increased safety can be achieved in use of the razor by timely indication of cutter foil wear.

FIELD OF THE INVENTION

The invention relates to an electric razor having a cutter foil and acutter head which interacts with the cutter foil and is driven by amotor which is possibly electronically pulsed, and having an indicatingdevice to recommend foil replacement.

DESCRIPTION OF THE PRIOR ART

In the case of such razors, which are known in various configurations,for example with a rotating or oscillating cutter head, the operatingreliability and the shaving result are to a large extent dependent onthe two mutually interacting parts which are intended to result in thefacial hairs being cut off. In addition to the blades of the head, whichare naturally subject to a certain amount of wear, the cutter foil isprimarily of critical importance to the desired result. Cutter foilshave a limited life, the risk of injury significantly increasing towardsthe end of the life of the cutter foils, and it no longer being ensuredthat the facial hairs are cut off smoothly. The risk of injury in thiscase increases not least because the originally specified geometricalshape of the openings in the cutter foil is no longer exactly maintainedand, even when the apparatus is switched off, sharp-edged projections onthe edge of the openings in the cutter foils can provide a cause ofinjuries.

In the case of an electric razor which is disclosed in DE-B-1,168,796,the cutter foil can adapt itself to the surface to be shaved and to thecutter head blade.

JP-A-3,218,791 has already disclosed such a razor, in which anindicating device is connected to an operating time counter in order toproduce a recommendation for foil replacement. An operating time counton the basis of an autonomous oscillator, for example of a commerciallyavailable clock module, allows the operating time to be determined as afunction of the on and off switch of the razor, and hence only arelatively coarse estimate of the actual wear of the cutter foil.

The wear to which the cutter foil is subjected is in this case dependenton the friction between the cutter foil and the sharpening block whichmoves in a positively locked manner relative to the cutter foil.Depending on the contact pressure of the cutter foil which is selectedby the respective user by operating the apparatus, the foil is nowmatched on the one hand to the contour of the face surface to be shavedand on the other hand to the contour of the cutter head, as a result ofwhich the wear is also highly dependent on the load and on the way inwhich the respective user uses the razor.

SUMMARY OF THE INVENTION

The invention now has the object of creating an electric razor of thetype mentioned initially, which is intended to ensure better estimationof the actual wear of the cutter foil and can produce a correspondingcutter foil replacement recommendation in order considerably to reducethe risk of injury to the user of the razor. In order to achieve thisobject, the razor according to the invention and of the type mentionedinitially comprises an indicating device being connected to a device fordetecting the load on the cutter foil and to an evaluation circuit.Alternatively, when using a pulsed motor, an improvement can be achievedby the indicating device being connected to an operating time counter,which is triggered by the pulsing of the motor, and to an evaluationcircuit. Such an indicating device, when it emits a correspondingsignal, provides the user with a recommendation for foil replacement andthus ensures that excessively worn cutter blades are also no longerused. The identification to the user of a razor of the correct time atwhich a cutter foil should be replaced is not directly measurable orpossible since a defective cutter foil is primarily identified byinjuries which have already occurred. However, as a result of such anindicating device according to the present invention, the time at whichinjuries could occur is now reliably indicated in advance, and thepossibility is created of replacing a cutter foil even before any injuryis possible.

An improved estimate of the actual wear of the cutter foil results ifthe operation of the indicating device also includes an evaluation ofother operating parameters of the razor, for example the powerconsumption or the like. The operating time count is thus advantageouslycombined with a device for detecting the load on the cutter foil andwith an evaluation circuit, it being possible for such a device fordetecting the load on the cutter foil and an evaluation circuit toproduce correct information for triggering the indicating deviceirrespective of a pure operating time count, as well. Alternatively, thedesign according to the invention can in this case be implemented suchthat the operating time counter is triggered by the pulsing of themotor, a combined statement on the load on the cutter foil beingpossible just by means of such a link between the time count and thepulsing of the motor.

The design according to the invention is implemented in a particularlyadvantageous manner in that the device for detecting the load on thecutter foil is formed by a current consumption measurement apparatuswhose measurements are connected to the indicating device via anevaluation circuit, especially an integrator. The integrated currentconsumption directly provides the capability of producing arecommendation to replace the cutter foil independently of the timewhich has actually passed, the integration of the current consumptionnaturally being effected via the current consumption in the unit time.

The design according to the invention can also be implemented in aparticularly simple manner in that the device for detecting the load onthe cutter foil comprises pressure sensors which interact with thecutter foil, such detection of pressure measurements additionally takingaccount of the most common operator parameters in using the electricrazor i.e., motor load compared to foil/cutter pressure.

In the case of electric razors, it has now become normal, particularlyin the case of the respective top of the range model, to provideindications of the remaining capacity of an accumulator. In the presentinvention, use of such a remaining capacity indication is linked to acertain amount of electronic complexity which, without any additionalcost, makes possible particularly simple generation of the correspondingsignals for the indicating device to recommend the foil replacement. Insuch cases, the design of the present invention is implemented in aparticularly advantageous manner, in that a change in the batteryvoltage or accumulator voltage in operation is evaluated as the signalfor detecting the load on the cutter foil.

Such an indicating device which provides information on the necessity toreplace the foil can be cancelled again in various ways. The inventionis in this case advantageously implemented by it being possible tocancel the indicating device via a switching contact which resets thecounter, the switching contact preferably being mechanically coupled tothe cutter foil and it being possible to operate it automatically whenthe cutter foil is replaced. Particularly when the switching contact ismechanically coupled to the cutter foil, resetting and cancellation areeffected immediately after the replacement of the cutter foil. Thedesign can in this case be implemented in a particularly simple mannersuch that the counting or evaluation circuit which is connected to theindicating device has a settable and resettable flipflop, which can beset by the counting or evaluation circuit and can be reset by aswitching contact, as a result of which the requirement is alsosatisfied with very little electronic complexity.

The invention is explained schematically in the following text, withreference to two block diagrams in the drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first design of the circuit arrangement with a simplecounting device; and,

FIG. 2 shows a schematic illustration of the combination of theevaluation of motor pulsing and oscillator signals.

FIG. 3 is a front view of an electric shaver having a foil replacementindicator.

FIG. 4 is a schematic representation of the circuitry of the instantinvention having a motor, battery, load detection circuit, and anindication means.

FIG. 5 is a schematic representation of the circuitry of the instantinvention having a motor, battery, pressure sensors and an indicationmeans.

DETAILED DESCRIPTION

In FIG. 1, 1 schematically indicates the motor pulsing. The motor pulseor a clock signal is fed to a time counter 2, the output signals beingpassed to the indicating device 4 via a resettable flipflop 3. Connectedto the resettable flipflop 3 is an external switching contact, indicatedschematically by 5, which brings about resetting of the flipflop andhence of the indicator or of the indicating device 4. In the simplestcase, the indicating device 4 can be formed by an LED or a suitablesymbol on an LCD.

In the design in FIG. 1, the time count can be implemented in thesimplest case such that the corresponding indication is produced on theindicator 4 after, for example, 30 or 35 operating hours.

In FIG. 1, reference S represents the output signal time counter,reference R represents the reset signal, and reference Q represents theoutput signal flip flop.

In FIG. 2, the motor pulsing is indicated schematically by the pulsesequence 6. At the same time, 7 indicates schematically the pulsewaveform of the oscillator signals. The signals, which in this way existin parallel, are supplied to an AND module 8 and from there areevaluated in a counter 9. The linking of the motor pulsing to theoscillator in this way also allows the load state to be identified andonly the signals linked in this manner are supplied to the counter 9 andfrom there to the flipflop 3 or to the indicator 4, as was illustratedin FIG. 1.

While the foregoing description of the invention has been provided forin an essentially schematic form, it is considered entirely enabling toone of ordinary skill in the razor field and one being familiar withconventional razors. For example the present invention can readily beadapted to the razors disclosed in U.S. Pat. No. 4,719,698 to Ninomiya,U.S. Pat. No. 4,380,121 to Naimer, and U.S. Pat. No. 4,408,392, also toNaimer. Each of the foregoing U.S. patents is incorporated herein intheir entirety by reference thereto.

The essential feature for reliable operation of the design according toFIG. 2 is that the oscillator frequency is selected to be considerablyhigher than the pulse frequency of the motor.

FIG. 3 illustrates an electric razor 20 having a cutter foil 22 and acutter head 24 which interacts with the cutter foil 22. As shown in FIG.4, the cutter head 24 is driven by an electric motor 26.

An indicating device 28 to recommend cutter foil replacement isconnected to a device for detecting the load on the cutter foil 22 andto an evaluation circuit 34.

The load detecting device may take several forms. For example, theindicating device 28 may be connected to load detection circuit 31comprising an operating time counter for the razor 20, which istriggered by the pulsing of the motor 26, and to the evaluation circuit34. In addition, the load detection circuit may include includes acurrent consumption measurement apparatus whose measurements areconnected to the indicating device 28 through the evaluation circuit 34,wherein the evaluation circuit 34 further comprises an integrator.Moreover, load detecting device may comprise pressure sensors 32 (seeFIG. 5) which interact with and sense pressure on the cutter foil 22.

As shown in FIG. 4, the razor 20 includes a battery 36 on anaccumulation and a change in the battery voltage or an accumulatorvoltage in operation of said razor is evaluated as the signal fordetecting the load on the cutter foil. The counting or evaluationcircuit 34 which is connected to the indicating device 28 has a settableand resettable flipflop, which can be set by the counting or evaluationcircuit and can be reset by a switching contact mechanically coupled tothe cutter foil 22. The switching contact can be operated automaticallywhen the foil 22 is replaced.

I claim:
 1. An electric razor comprising:a cutter foil and a cutter headwhich interacts with the cutter foil and is driven by an electric motor;and, an indicating device to recommend cutter foil replacement, saidindicating device being connected to a device for detecting the load onthe cutter foil and to an evaluation circuit.
 2. An electric razorcomprising:a cutter foil and a cutter head which interacts with thecutter foil and is driven by an electrically pulsed motor; and, anindicating device to recommend foil replacement, said indicating devicebeing connected to an operating time counter for said razor, which istriggered by the pulsing of the motor, and to an evaluation circuit. 3.A razor according to claim 1: wherein said device for detecting the loadon the cutter foil includes a current consumption measurement apparatuswhose measurements are connected to said indicating device through saidevaluation circuit, said evaluation circuit further comprising anintegrator.
 4. A razor according to claim 1: wherein,said device fordetecting the load on the cutter foil comprises pressure sensors whichinteract with and sense pressure on the cutter foil.
 5. A razoraccording to claim 1: wherein said razor includes a battery on anaccumulation and a change in the battery voltage or an accumulatorvoltage in operation of said razor is evaluated as the signal fordetecting the load on the cutter foil.
 6. A razor according to claim 2,wherein:said indicating device can be cancelled via a switching contactwhich resets said counter.
 7. A razor according to claim 6, wherein:saidswitching contact is mechanically coupled to said cutter foil and can beoperated automatically when said cutter foil is replaced.
 8. A razoraccording to claim 6, wherein:said evaluation circuit which is connectedto said indicating device has a settable and resettable flipflop, whichcan be set by the evaluation circuit and can be reset by said switchingcontact.